Pregnancy and birth complications in autism and liability to the broader autism phenotype

The sample included 78 children with an autism spectrum disorder and 88 unaffected siblings. A standardized interview was used to ask mothers about the pregnancy and birth of each child, and an overall index reflecting freedom from complications (termed "optimality") was determined. The presence of autism-like traits (termed the "broader autism phenotype") in second- and third-degree relatives was ascertained by reports from multiple informants. The pro-. portion of relatives with the broader autism phenotype, corrected for degree of relation, was used as an index of family loading. Children with autism spectrum disorders have lower optimality (higher rates of complications) than unaffected siblings. High family loading for the broader autism phenotype is associated with higher rates of complications in unaffected siblings. Family loading was not significantly associated with complications in affected siblings in this sample.